1. Technology Field
The present invention generally relates to dielectric films. In particular, the present invention relates to structures and methods for measuring the thickness and dielectric permittivity of dielectric films deposited on a substrate.
2. The Related Technology
Accurate measurement of film thickness is an important problem in a wide range of applications. For example, such measurements are fundamental in microfabrication processes, such as chemical vapor deposition, molecular beam epitaxy, thermal oxidation, diffusion, and sputtering, and are essential in many biological and biomedical applications.
Various physical principles can be used to non-invasively estimate film thickness, including interferometry, sample weighing, x-ray photoelectron spectroscopy, wavelength scanning, ellipsometry, coherence tomography, and analytical electron microscopy. Unfortunately, most of these available techniques are limited to certain types of films, or may not be suitable for making in-situ measurements in real time.
A need therefore exists for a method by which film thickness deposited on a surface having a simple or complex geometry can be determined. Moreover, a need exists for such measurement to be performed at the location of the film and in real time, thereby enabling such measurement in locations previously unmeasurable or in environments with changing film thickness and properties. Also, it would be desirable to provide simultaneous dielectric permittivity and thickness measurements, thereby providing the ability to monitor in real time changing chemical or electrical characteristics of the film.